My understanding is that an RCA cable output is likely balanced if the ground wire is separate. If it's incorporated into the cable one must assume that it is not balanced. My phono pre (Austin Audio Works) has a switch for balanced vs. unbalanced input. I don't know if there would be any benefit for running a balanced out from your preamp even if the input from the TT was unbalanced, although guess you could always hook it up either way way and listen to it.
